Can't add anything to what's already been posted but I would like to add my encouragement and support. What you are experiencing is not unusual. If you haven't done rolls before it can be a daunting prospect in the beginning and there's a lot to know and do all at the same time.

So please don't be discouraged and keep training. I guarantee that you will see improvements in time. Enjoy the training sessions.

Just a case in point, some students were having some problems with forwards and backwards rolls but after about 6 months of regular training doing some of the things that have been suggested in the previous posts they started to get the idea and their rolls were a lot smoother and less "clunky". It was great to see their progress and I am sure that in time you will get the same results.